It all depends on the scoring format.
Handcuffing is a strategy for certain types of players and often best suited for certain types of scoring formats.
Some leagues allow the backup to accumulate points for their starter if the starter goes down and they own the handcuff. I don't play in any leagues like that.
IMO, handcuffing is also a strategy to cover some bases for very high value players who happen to have a backup that is very high value. Ex: Foster and Ben Tate. This can also be done so that losing said player doesn't allow a fellow member to dismantle your team because you now have need, ex: someone else owns Ben Tate, Foster goes down, and now they want to trade you Ben Tate for your remaining super stars. At the end of the day though, ask several ppl and you'll get differing answers as to what "handcuffing" means to them. Again, all relative to the league's format.
Anyhow, question remains, Geno Smith, Gabbert or Fitzpatrick tomorrow? IMO conservative play is Fitzpatrick, and Geno Smith is the upside play with more risk.